Kwang-il Hwang

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Concurrent access among multiple mobile readers brings about a new problem called reader collision that a reader’s transmission is interfered by the others. There have been several works to solve the reader collision problem. While they employ time division, frequency division, space division, or centralized scheduling approach, in this paper, we(More)
Wireless sensor networks consisting of hundreds to thousands of nodes are expected to find increasing deployment in coming years, as they enable reliable monitoring and analysis of physical worlds. These networks have unique features that are very different from traditional networks, e.g., the very large number of nodes, limitation in power. Due to these(More)
Advances in wireless and mobile communication technologies have enabled the development of various RFID-based systems and applications in addition to the extension of the tag reading range of mobile readers. Thus, it has become commonplace that multiple readers concurrently attempt to read tags within ranges of the readers. However, this concurrent access(More)
Sink mobility creates new challenges for several sensor network applications. In mobile sink environments, each sink must propagate its current location continuously, through a sensor field, in order to keep all sensor nodes updated with the direction of data forwarding. This method consumes large amounts of energy. Although several protocols, such as DD,(More)
Recently, the development of the Internet of Things (IoT) applications has become more active with the emergence of low-power wide-area network (LPWAN), which has the advantages of low-power and long communication distance. Among the various LPWAN technologies, long-range wide-area network (LoRaWAN, or LoRa) is considered as the most mature technology.(More)
In a wide sensor field, it is difficult to track location of moving targets to just fixed sinks, since data aggregation can be slower than the movement of targets. In such applications, some of mobile sink users can be directly injected to the sensor filed. So, in recent, the problem handling multiple mobile sinks in wireless sensor networks is becoming(More)